Cape Town - The Lions and their CEO, Rudolf Straeuli, are fighting with all their might to keep Springbok lock Franco Mostert at Ellis Park in 2019.
ALSO READ: Straeuli says NO to top Bulls job
The 27-year-old has been in superb form for the Lions and Springboks in 2018 and is the frontrunner to wear the No 5 jersey at next year's Rugby World Cup in Japan.
English club Gloucester, however, announced earlier in the year that Mostert would be joining them from the beginning of the 2018/19 season.
It is a move that would see Mostert reunited with former Lions coach Johan Ackermann.
But, speaking to the Citizen, Straeuli said that the union was intent on keeping Mostert and that there had been irregularities in the signing.
"Franco is still contracted by us and we are still in the middle of a dispute with Gloucester," he said.
"He must honour his contract, with all respect to Franco, but my board told me I must act against Gloucester.
"His agent had been suspended for three years and it has happened before with Lyon in France, and the second time we said 'no'."